A conventional punch for punching holes through document is disclosed in FIGS. 6 and 7, and generally includes a base 80 with a base plate 70 mounted thereon so as to define a space for receiving paper debris. A frame 65 is fixedly to connection holes 71 defined in the base plate 70. The frame 65 has slots 651 defined in an upright portion thereof and punch units 60 are fixed to the upright portion of the frame 65 by extending bolts 64 through the slots 651 and connected to respective casings 63 of the punch units 60. Each casing 63 has a punch member 61 connected thereto and a spring is received in the casing 63 and mounted to the punch member 61. Each casing 63 further has a hole defined in an underside thereof so that the punch member 61 may extend through the hole and insert into a through slot 72 defined in the base plate 70. A handle 50 is pivotably connected to two lugs 73 on the base plate 70 and includes several protrusions 51 which project from an underside of the handle 50 so that when the user pivots the handle 50 downward, the protrusions 51 push the punch members 61 downward to penetrate the document 90 inserted in the receiving slot 631 of each of the punch units 60. It is noted that the base plate 70 tends to be bent by the huge downward force coming from the punch members 61. Besides, it takes a lot of time to assemble the punch units 60 to the frame 65.
Referring to FIG. 8, an improved structure of the punch is developed and the punch units 60 are connected to the base plate 70 directly by bolts 64 from an underside of the base plate 70. Each punch unit 60 has an engaging edge 632 which extends downward and is engaged with a recess 74 defined in a front side of the base plate 70. Nevertheless, the engagement of the engaging edge 632 and the recess 74 cannot provide a desired feature so that the punch units 60 could rotate about the bolt 64. In addition, when inserting document into the receiving slot 631 of the punch unit 60, the sheets of the document could be tangled by the gap between the engaging edge 632 and the surface of the recess 74.
The present invention intends to provide a punch that the punch units each have positioning blocks for securely connect the punch units on the base plate. The base plate has a ridge extending from a top surface of the base plate so as to guide the document into the receiving slot of each punch unit.